Starting and operating circuit for gaseous electric discharge devices



1944. M. A. BABE 2,3415% STARTING AND OPERATING CIRCUIT FOR GASEOUSELECTRIC DISCHARGE DEVICES Filed Feb. 20, 1941 moammomnmn 40- h E I l 4/50 ATTORNEYS Patented Feb. 1944 2,341,520 I STARTING AND OPERATINGCIRCUIT FOR GASEOUS ELECTRIC DISCHARGE VICES Maynard A. Babb, Tenafly,N. J. Application February 20, 1941, Serial No. 379,756 19 Claims. (Cl.315-100) The present invention relates primarily to hot electrode vaporor gaseous electric discharge devices commonly embodied in hot cathodegaseous lamps and while it has an important application to fluorescentlamps of that type, it is not limited to such devices.

As conducive to a clear understanding of the invention, it is noted thatwhen a lamp of the above type becomes defective, as for instance due towearing or chipping ofl of the emissive filament coating or for otherreasons, the arc strikes with difllculty and does not maintain itself,so that the lamp flashes on and off intermittently at short irregularintervals, as long as the lamp is in circuit, resulting in annoyance toall persons in the vicinity of the defective lamp, in waste of power andin rapid destruction of the starting interrupter.

While the magnetic type of starting interrupter has importantadvantages, among other reasons, because of its rapid cycle and theconsequent effectiveness of ballast kick which facilitates starting, therapid destruction noted, due to pitting of its contacts in the prolongedrapid make and break thereof with a defective lamphas militated againstits wider use.

Though they impart a less effective ballast kick, the thermal and theglow switch type of l starting interrupters have been extensively used,since their relatively slow operating cycle leads to long life thereof,provided however that the switches, which in many instances have a lifeno greater than that of the lamp.

It is among the objects of'the invention automatically to protect any ofthe familiar types of starting interrupter (regardless whether the samebe of the magnetic, the thermal, the glow switch or other type, whenused in any of the conventional circuits), from further operationthereof, if the lamp should be so defective as not to maintain its areat the end of the brief interval adequate in normal starting operation.

Another object is to provide simple means whereby the starting impulsesupon the lamp are and remain inhibited, except for a brief interval 'ofintermittent flashes upon each closure of the main switch which apprisesof the need for replacement, and in which the act of removal of thedefective lamp results automatically in restoring the lamp startingdevice to operativeness.

Essentially the invention involves the use of a self-closing time delayswitch, opened due to the prolonged starting current in the attemptedstarting of a defective lamp, to interrupt the starting connectionbetween the electrodes and to complete a normally open by-pass circuitthat has circuit characteristics such as to pass suflicient current toprevent the time delay switch from reclosing, thereby to inhibitstarting impulse upon the lamp. The time delay switch is desirably ofthe temperature controlled, preferably of the bi-metallic snap switchtype, which rspondsto the heat generated by undue prolongation of thestarting current.

In the accompanying drawing in which are shown one or more of variouspossible embodiments of the several features of the invention,

Fig. 1 is 'a diagrammatic view of one circuit incorporating theinvention,

Fig. 2 is a view similar to Fig. 1 showing one application of theinvention to a lamp of higher voltage,

Fig. 3 is a view similar to Fig. 2, showing an embodiment of theinvention applied to power factor and stroboscopicaliy corrected twolamp circuits, and

Fig. 4 is a view similar to Fig. 3 showing a desirable application tolow-voltage lamps.

Referring now to Fig. 1 of the drawing, the conventional lamp L is shownwith electrodes, illustratively filaments e' and e at opposite endsthereof, each coated with electron emissive material such as bariumoxide, according to conventional practice.

The starting interrupter is in the starting circuit III, which connectselectrodes e' and e in series. Said interrupter which may be of any ofthe conventional types, such as the magnetic, the thermal or the glowswitch type, is shown diagrammatically at I in the open position tointerrupt the starting circuit as long as the lamp is arcing and it hasthe usual condenser 9 thereacross. The circuit includes an iron coreballast coil l2 in main i3 which aids in starting, by imparting aninductive kick each time the starting interrupter opens. The lowering ofthe power factor of the system due to said ballast coil is compensatedfor by condenser l5 across the mains II and Il, all in accordance withconventional practice..- Upon closing of the main switch II theelectrodes e and e are heated due to the flow of current in seriestherethrough by way of the starting circuit it which includes the closedinterrupter I. As the interrupter opens under the impulse imparted bythe magnetic, thermal, glow or other operating instrumentality, inresponse to the starting current, the break down of flux in col] l2assists striking of the arc. If the lamp fails to flre the interrupterwill reclose and the cycle will be repeated until the lamp has fired,

whereupon the interrupter I will remain open due to the action of themagnetic, thermal or glow device, in manner well understood.

According to the invention, there is included in the series connection lbetween the electrodes a self-closing time delay switch, preferably athermally operated switch I8, desirably of the bi-metallic type, closedat contact IT. The switch l8 may be operated from an electric heater Itin the series connection ill or may be of the type in which the currentis passed directly through the bimetallic element, In the case of anoperative or perfect lamp the switch It remains in engagement with itscontact I! and the circuit operates in the conventional manner. In thecase of a defective lamp, however, the current passing through thestarting connection ill in the attempted starting operation is continuedunduly because of the failure of the lamp to are, and so generatessufflcient heat in the heater It to deflect the switch it away fromcontact l1, thereby to open the starting connection.

With the use of the equipment thus far described, th objectionableflashing of a defective lamp would not be inhibited. because uponcooling after interruption of the starting circuit, switch It wouldreclose and the objectionable flashing would resume and that actionwould continue as long as the main switch I i remains closed. To preventsuch resumption of flashing, mean is provided to pass enough current tothe heater I8 of switch It in its deflected position. to preventrecicsure thereof as long as the defective lamp remains in circuit withthe main switch ll closed. In Fig. 1, a by-pass lead 20 connected tomain H has a contact II to be engaged by the deflected bi-metallicswitch 46. The normally open by-pass circuit. when thus closed, extendsfrom main it to ballast coil l2 to electrode e. heater i8, switch 5,.contact 2| and by-pass lead 20 to the other main I. The by-Dass circuithas characteristics such that it passes only sufflcient currenttherethrough to maintain the temperature responsive switch It indeflected position. To this end, while the by-pass circuit may include asuitable resistance, it-is preferred to use an inductance 22 to impartto said circuit an impedance such, as desirably to pass a current, sayof .3 amperes, which is less than that necessary to deflect thebi-metallic switch, but suiflcient to maintain it in deflected position.Desirably, the bi-metallic switch I0 is of the familiar snap switchconstruction to assure prompt shift from contact I! to contact 2| and topreclude ,inoperativeness due to a floating of the switch arm betweenthe contacts.

Thus with a defective lamp, after intermittent flashing for say six orseven seconds, sufficient heat will have been evolved in the heater I!to cause the deflection of switch It; The starting impulse on the lampis now inhibited, since the current through the by-pass circuit,maintains the heater ll active to prevent return of the deflected switchIt, which maintains the by-pass circuit closed or completed by itsengagement with contact II. the destruction of the starter contactswhich would be incurred by the intermittently repeated make and breakthereof which would occur in the conventional circuit when the lampbecomes defective. Particularly in the case of circuits inlamp on andoil for a few seconds after starting apprises the user of the need forreplacement. But the annoyance is obviated of repeated flashing for manyminutes or hours, which otherwise is experienced whena relativelyinaccessible lamp becomes defective. Opening of the main switch I l orremoval of the defective lamp, even though the main switch remainsclosed, results in interruption of the circuit to heater l8 so that theswitch it automatically returns to engage contact I1, and a replacementlamp will start without the need for any manipulation to restore thestarting circuit to operativeness. 1

In the embodiment of Fig. 2 is shown the application of the invention toa lamp which requires a higher voltage. Illustratively the supply main25 and 26 for this purpose are connected across the low voltageterminals of an auto transformer 21, the high voltage terminals of whichare connected respectively to electrode e and electrode e of th lamp L.The starting interrupter, illustratively of the magnetic type, isoperated by an electromagnetic coil which may be coil 28 interposedbetween auto transformer 21 and electrode e. Condenser 29 bridges acrossthe interrupter contacts according to familiar practice.

The by-pass circuit lead is devoid of the coil 22 used in the embodimentof Fig.1. Lead 30 is connected to a tap ll close to the grounded side ofthe auto transformer 21. The remaining elements are identical with thoseof Fig. 1 and corresponding D rts bear the same reference numerals withexponents 2.

In operation, when due to a defect in the lamp the thermally responsiveheater I6 is excessively heated, switch I is deflected to enga e contact2| and to close the normally open by-pass circuit. The electromotiveforce applied to the bypass circuit by the auto transformer section 32between main 25 and tap 3| now causes flow of current through theby-pass circuit. Ordinarily, only sumcient turns of the auto transformerare in the by-pass circuit to impose for example I! may comprise an ironcore transformer havingfa" primary coil 40 across the mains and I2 andtwo secondary coils l3 and II extending in opposite directions, thelatter having a condenser Accordingly, there is avoided compensated lamppair of low voltage.

45 in series therewith, and being closer to the primary than is coil 43,for different leakage inductance thereof.

The two fluorescent lamps are shown at L' and U and are connected acrossthe respectivesecondary coils 43 and 44 of the ballast unit B. Thereference numerals are applied to only one of the lamps, the other beingidentical therewith,

and with the lamps shown in the other embodi- The starting circuitextends from main 42 to I the secondary coil it, the coil 44 in lead 45to electrode e, the starting switch I under control of coil M, thence tothe bi-metallic heater switch it with its heater coil I8 said switchnormally engaging contact H to close the series circuit throughelectrode e to the opposite main 4!. An otherwise conventional two lamphigh power factor ballast unit B has a tap 48 close to the grounded endof the primary coil 40, which is connected by lead 4i to the connection48 be tween, the normally inactive contacts 2i of the by-pass circuitsfor the respective lamps.

The operation which will be clear from the foregoing description, willnow be briefly summarized. In the normal operation of the lamps thecondenser 45 in combination with the flxed leakage inductance ofsecondary coil 44 will effect a phase difference in the operation of thetwo lamps sufficient substantially to eliminate the stroboscopic effectand greatly to improve the power factor in manner well known to thosekilled in the art.

If either of the lamps should become defective, then according to theoperation previously described, the time delay switch I8 of suchdefective lamp will be caused to deflect and snap over to interrupt thestarting circuit at I I and to close the by-pass circuit at contact 2".The switch I is kept in its deflected position by the currentcontinuously passing through the now closed by-pass circuit, whichderives its electromotive force from the section 50 of the primarybetween main 4i and tap l6 and that circuit is closed from main 4|through electrode e, heater coil ll! of switch I8 contact H andconnectors 48 and 41 to tap 46. Thus, a single source of electromotiveforce, i. e., the section 50 of the two lamp high power factor ballastwill prevent reclosure of either bi-metallic switch Iii once such switchhas opened due to defectiveness of the corresponding lamp. Theinhibition of further flashing of a defective lamp thus occurs withoutinterfering with the continued operation of the companion lamp as longas the same remains operative. In the embodiment of Fig. 4 is shown anapplication of the self-closing time delay by-pass switch to a powerfactor and strobosccpically The two lamp high power factor ballast unitB is substantially conventional and illustratively comprises two ballastcoils 60 and GI connected in main 82, respectively to electrode e oflamp L and the corresponding electrode of lamp L Ballast Si is ofleakage inductance'differing from that of ballast 60 and has aconventional condenser 63 in series therewith which may have aresistance 64 across the terminals thereof.

Where, as illustratively shown, a starting inter-' rupter G of the glowswitch type with the usual condenser thereacross is used on each lamp,the

till

conventional compensator C may be connected in series with one of theglow switches G, shown as that for lamp L. That compensator serves toadjust the starting current and to prevent the lamp L" from taking acurrent diiferent from that supplied to the companion lamp L. Thecompensator may comprise the usual inductance I! with condenser l6thereabout if desired., and is also a part of the conventional unit B.Where instead of the glow switch, a magnetic, thermal or other startinginterrupter is employed, the compensator 0 might be omitted from unit B.

According to the present embodiment. a reactance. desirably an inductiveelement 41 shown as an auto transformer is connected across the mains totake the full voltage and a tap 88 therefrom near the grounded side 49thereof, is connected in parallel to the two contacts 2 l of the bypassor hold-out circuits. Maniiestly the inductive element 61 could also beand preferably would .be built into the unit B. The operation is cleartyp it will be understood that in each of the embodiments any of theknown types of switches.

includingthe magnetic, the thermal and the glow switch, could beemployed.

As many changes could be made in the above methods and circuits and manyapparently wide ly different embodiments of this invention could be madewithout departing from the scope of the claims, it is intended that allmatter contained in the above description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

Having thus described my invention, what I. claim as new and desire tosecure by Letters Patent is:

1. In hot electrode vapor lamp operation, the method of automaticalyexcluding from an operating circuit a defective lamp which otherwisewould flash on and off intermittently throughout operation, whichmethod'consists in uti izing the prolonged starting current evolved inthe intermittent starting of such lamp upon each closure of theoperating circuit to effect opening of the lamp starting circuit andclosing of a by-pass and feeding sufllcient current through the bypassto prevent reclosure of the lamp starting circuit as long as theoperating circuit remains closed and to cause suchyeclosure to occurwhen the operating circuit is opened.

2. In hot electrode vapor lamp operation, the method of automaticallyexcluding from an operating circuit a defective lamp which otherwisewould flash on and oil intermittently throughout operation, which methodconsists in utilizing the prolonged starting current evolved in theintermittent starting of such lamp upon each closure of the operatingcircuit to exert displacement by thermal expansion to effect snapopening of the lamp starting circuit. and thereupon passing sufflcientcurrent to evolve the heat required to maintain said thermal expansion,thereby to prevent reclosure of said lamp starting circuit as long asthe operating circuit remains closed and to cause such reclosure tooccur when the operating circuit is opened.

3. In a safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes, 9. connection forfeeding alternating current through said electrodes in sponse to theprolonged starting current in the attempted operation of a defectivelamp, and means to maintain said time delay switch in said operatedposition as long as the control switch is closed and to release the timedelay a switch in response to the opening of the control switch. 3

4. The arrangement defined in claim 3 in which the time delay switchresponds to temperature changes and the means last recited in claim 3comprises an impedance in the safety circuit, permitting the passage ofenough current therethrough to maintain a temperature suiiiciently highto keep said switch in operated position 5. In a safety starting andoperating circuit for vapor electric discharge devices equipped withspaced electrodes, means effective to establish a series connectionthrough said electrodes, means to interrupt and maintain interruptedsaid con nection when the arc of the lamp is struck and as long as it ismaintained, a normally open bypass line connected with a difference ofpotential between its terminals, a temperature responsive switchsubjected to the heat evolved in the starting circuit due to startingcurrent and arranged to interrupt said series connection under theexcess heat generated in the attempted starting of a defective lamp andto close circuit through said by-pass line, said by-pass line havingcircuit characteristics such as to pass sufiiclent current to keep thetemperature responsive switch in deflected position.

6. In a safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes, a series connectionbetween said electrodes, means to interrupt and maintain said seriesconnection interrupted while the lamp is arci g. a bi-metallic switchhaving a heater normally in said series circuitand arranged to bedeflected and to eflect opening of the latter under the excessive heatgenerated by the prolongd starting current passed in the attemptedstarting of a defective lamp and a bypass circuit having a gap thereinbridged by said bi-metallic switch when deflected, thereby to closecircuit therethrough, said by-pass circult having characteristics toassure continuance ofcurrent through said heater suflicient to maintainthe bi-metallic switch in deflected position.

7. In a safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes, a startinginterrupter, a series connection between said electrodes under controlof said interrupter to feed current' when the latter is deflected, s'aidby-pass circuit including said heater therein and having characteristicssuch as to pass suiiicient current to maintain the iii-metallic switchin deflected posi on.

8. A safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes, comprising a ballastcoil connected to one of the electrodes, a series connection betweensaid electrodes, a starting interrupter in said connection, said seriesconnection including a bi-metahic switch closed in normal operation anddeflected under the prolonged starting current and the resultant heatevolved in the attempted starting of a defective lamp, a normally openby-pass lead having terminals at different potentials, said bi-metallicswitch when thus deflected closing the by-pass circuit,

' said latter circuit having characteristics such that the currentthrough the bi-metallic switch is sufllcient to maintain the same insaid de- 1 to maintain said connection interrupted while through saidelectrodes in series, means for autothe lamp is functioning, aself-closing time delay switch in said series connection deflected bycurrent conditions under abnormal starting operation to open thestarting circuit and a normally open by-pass'circuit closed by saidswitch when deflected, said by-pass circuit having an element therein toimpart to it the characteristics required to maintain sufiicient currenttherethrough for preventing the switch from reclosing and retaining itin deflected position.

- 10. A safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes comprising a seriesconnection between said electrodes having a starting interrupter thereinto open and be maintained open during normal functioning of the device,a selfcloslng time delay switch in said series connection adapted toopen by the prolonged current passed in abnormal starting operation anda normally open by-pass circuit adapted to be closed by said switch whenin deflected position, said by-pass circuit having an inductance thereinof value to impart the required characteristics for passing therethroughsufliclent current to maintain said switch in deflected position.

11. In a starting and operating circuit for gaseous electric dischargedevices of the high voltage type equipped with spaced electrodes, anauto transformer having a primary coil across the current leads, thehigh voltage secondary coil being connected across the discharge device,a series connection between the electrodes, a starting ginterruptertherein maintained open while the arc exists across the electrodes, andmeans for automatically maintaining said interrupter out of operation inthe case of a defective lamp, said means comprising a bi-metallic switchin said series connection, a normally open by-pass circuit leading fromoneterminal to a part of the circuit at a different potential, saidbi-metallic switch being deflected under the heat generated by theprolonged starting current in the attempted starting of a defective.lamp to open said series connection and close said by-pass circuit, saidby-pass having circuit characteristics such that suiilcient current ispassed therethrough to maintain said bi-metalli switch in deflectedposition.

- 12. A safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes, comprising a ballastcoil in one of the circuit leads connected to one of the electrodes, abi-metallic switch closed in normal operation, deflecting means for saidswitch operative under current conditions in starting a defective lamp,a'normally open by-pass circuit closed by said bi-metallic switch whenthus deflected, said by-pass circuit being connected for applicationthereacross of a fraction of the line voltage, to pass through theswitch deflecting means sufficient current to maintain the bi-metallicswitch in deflected position.

13. In a safety starting and operating circuit for gaseous electricdischarge lamps equipped with spaced electrodes, a reactive device incircuit with said lamp for applying operating voltage therelatter isdeflected by heat applied thereto under abnormal starting operation,said by-pass circuit having terminals connected across a number of turnsof said auto transformer for impression thereon of voltage suflicient tomaintain said switch in deflected position.

16. In a safety starting and operating circuit, a pair of mains, areactive unit having a pair of terminals connected to said mains, aplurality of gaseous electric discharge devices, each equipped withspaced electrodes, each of said lamps having an associated startingcircuit connecting the electrodes thereof-in series, each of said seriesconnections having an element therein to be maintained open duringnormal functioning of the device, and also having a switch adapted toopen under the current conditions in abnormal starting operation, anormally open by-pass circuit to, a starting circuit for passing currentthrough said electrodes in series during the starting oper-- ation,means for interrupting said circuit as long as the arc is establishedacross the lamp, a selfclosing time delay switch in the starting circuitand responding to the prolonged starting current in attempted startingof a defective lamp, a normally open by-pass circuit closed by saidswitch when the latter is deflected due to a defective lamp, saidby-pass circuit being connected across a portion of said reactivedevice.

14. In a safety starting and operating circuit for gaseous electricdischarge devices equipped with spaced electrodes, an auto transformerhaving a stepped up secondary coil applied across the discharge device,means connecting said electrodes in series during the startingoperation, said means having a starting interrupter therein maintainedopen while the device is arcing, said means also having a self-closingtime delay snap switch therein opened in response to the current passedin abnormal starting operation, and a normally open by-pass circuithaving terminals con-- nected across a small segment of said autotransformer, said circuit being completed by the opening of said switchand maintained completed by current through the by-pass circuit underthe impressed voltage from said auto transformer, thereby to preventreclosure of said switch.

15. In a starting and operating circuit for gaseous electric dischargedevices of the high voltage adapted to be completed. by said switch whenin open position, the by-pass circuits of the several lamps having acommon source of electromotive force, said common source comprising ashort section of said reactive unit.

1'7. The combination recited in claim 16 in which the reactance is aninductance across which the several lamps are connected, the severalby-pass circuits being connected across a short section ofsaidinductance at the grounded end thereof. e V

' 18. In a power factor and stroboscopically corrected vapor electricdischarge lamp system of the type comprising a two lamp high-powerfactor ballast, a pair of gaseous electric discharge lamps connectedwith said ballast, each having spaced electrodes and each having aseries starting connection between said electrodes; the combination ofmeans for automatically removing from circuit either ofthe lamps whenthe same i is defective. said means comprising a self-closing time delayswitch in the starting connection, a normally open by-pass circuitclosed by the opening movement of the switch, the by-pass circuits ofthe two lamps being supplied by electromotive force evolved from theballast.

19. In a power factor and stroboscopically corrected vapor electricdischarge lamp system of the low voltage type, a two lamp high powerfac- VI tor ballast, a pair of gaseous electric discharge type andequipped with spaced electrodes,. an

auto transformer across the current mains, having a high voltagesecondary across the discharge delamps connected with said ballast, eachhaving electrodes and each having a series starting connection betweensaid electrodes the combination of means for automatically removing fromsaid circuit either of the lamps when the same is defective, said meanscomprising a self-closing time delay switch in the starting connection,a normally open by-pass circuit closed by the opening movement of theswitch, a reactance connected across the mains, the by-pass circuits ofthe two lamps being supplied by electromotive force across a small partof the reactance.

MAYNARD A. BABB.

